Dislocation reduction in heteroepitaxial Ge on Si using SiO2 lined etch pits and epitaxial lateral overgrowth

We report a technique that significantly reduces threading dislocations in Ge on Si heteroepitaxy. Germanium is first grown on Si and etched to produce pits in the surface where threading dislocations terminate. Further processing leaves a layer of SiO2 only within etch pits. Subsequent selective epitaxial Ge growth results in coalescence above the SiO2. The SiO2 blocks the threading dislocations from propagating into the upper Ge epilayer. With annealed Ge films grown on Si, the said method reduces the defect density from 2.6 x 10(8) to 1.7 x 10(6) cm(-2), potentially making the layer suitable for electronic and photovoltaic devices. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3632113]